CIRCULATORY SYSTEM IN COCKROACH

Type is open or lacunar. i.e. b.v. absent. Organs are dipped in haemolymph.

1.      HAEMOLYMPH -

Blood and lymph are mixed. In plasma corpusulses or haemocyte present.

Haemocytes are euqal to W.B.C. and are of 2 types -

(i) Proleucocyte - small nucleus, large in size, produce antibodies.

(ii) Phagocyte - Large nucleus, small in size, engulf harmful bacteria.

In haemolymph Na+ & Cl- present.

In it free amino acids present function as asmotic regulation. Trehalase sugar present.

2.      HAEMOCOEL -

True coelome, schizocoelic, filled with haemolymph.

Due to dorsal & ventral porous septa coelome is divided in to three compartments -

(i) Pericardial - heart                        

(ii) Perivisceral - gut                   (Largest)

(iii) Perineural - Nerve cord            (Smallest)

Coelome is too much degenerated present only in reproductive area & some glands.

By dorsal septa haemolymph flows from perivisceral to pericardial only not vice versa.

By ventral septa haemolymph flows from perineural sinus to perivisceral sinus and vice versa.

Note :- Haemocoel is obliterated. true coelome i.e. flattened dorso-ventrally.

3.      HEART -

1. Tubular, situated on dorsal side, flow of blood posterior ® anterior, in complete length, made up of 13 chambers (3 thoracic + 10 abdominal).
2. First chamber is largest one, open in perivisceral sinus of head sinus. Last chamber is closed at base.
3. Between 2 chambers, on lateral side 1 pair fenestrae or ostia present controled by auricular valve, allow haemolymph to enter in to heart chamber not vice-versa. In anterior part of heart chamber ventricular valve present.
4. On lateral side of heart 13 pairs allary muscles present which are V-shaped. Pointed end is attached to tergum & flat end to dorsal septa.

Note :- Heart is Neurogenic but in anopheles and some other insects it is myogenic.

4.      MECHANISM

1. First of all allary muscles are relaxed, volume of pericardial sinus is increased & so pressure is decreased, so blood comes from perineural & perivisceral to pericardial sinus.
2. Allary muscles are contracted, volume of pericardial sinus is decreased & pressur is increased, so blood enters into heart's chamber. This time auricular valves are open and ventricular valve are closed.
3. Allary muscles are relaxed, volume of pericardial sinus is increased, at the same time blood moves from posterior to anterior in heart and comes in perivisceral sinus of head sinus & to perineural sinus of body. this time ventricular valves are open & auricular valves are closed.
4. Perineural sinus supply blood to leg. Perivisceral sinus collect blood from leg.
5. Peri visceral sinus supply & collect blood from wings. At the base of wings, legs and antennae pulsating ampullae present.
6. Heart beat 49 / minute. Gape between 2 systole is diastasis.